The present invention relates to the cable suspension arts. It particularly relates to apparatus and methods for suspending high tension cables mounted aerially using poles or other overhead support structures, and will be described with particular reference thereto. However, the invention also finds application in conjunction with other uses where cables for the transmission of power or communication signals are fastened, clamped, affixed, or otherwise mechanically supported or constrained, such as in the suspension of optical ground wires (OPGW""s).
Power cables are frequently suspended aerially from poles or other support structures. An aerial arrangement of such cables has the advantages of relatively simple and flexible installation having a limited ground footprint, and permits space substantially below the cables to be used for other purposes. An aerial arrangement also separates the cables from contact with people or roaming ground animals. Spatial separation is particularly important for high tension electrical power transmission cables for safety reasons. Separation of any cable helps protect the cable from damage caused either inadvertently or through malicious vandalism.
Although aerial cables are relatively safe from ground-based sources of damage, they are subject to environmental wear and damage, principally due to winds. Well known in the art are problems caused by aeolian vibration which is a high frequency, low amplitude vibration caused by laminar winds passing across the line, as well as galloping which is a low frequency, high amplitude wind-induced cable motion. Aeolian vibration, galloping,, and other wind action can produce cable damage especially at the suspension points where cable clamps and other supporting devices mechanically stress the cable. Cable damage in the form of abrasion, wear, and fatigue can occur especially at the clamping points.
The prior art includes a large number of cable clamp styles. A type of clamp commonly used for high tension power cable suspension employs a pair of upper and lower clamp body portions that sandwich the cable in vertical fashion (top-and-bottom) and are clamped using bolts, rods, or other fasteners. These cable clamps are formed from a plurality of parts which remain separate until assembly in the field. This being the case, the bolts, rods, or other fasteners are susceptible to misplacement or mishandling in the field, particularly in rainy, snowy, or other adverse weather conditions. The fastening of the clamp usually requires simultaneous manipulation of both a bolt and an associated fastening nut in order to effectuate the clamping. This requires two hands, and can be particularly problematic when installing the clamp on an electrified cable. Furthermore, two dissimilar clamp body portions are paired to form the clamp body, further increasing the possibility of encountering missing clamp parts during field assembly. As the two clamp halves are mounted above and below the cable, the clamping force is added to the weight-induced bending stress of the cable.
U.S. Pat. No. 2,887,669 issued to J. Sylvester discloses a cable connector having two identically formed clamp body portions, which reduces the number of differentiated parts. U.S. Pat. No. 3,633,858 issued to H. J. Houston et al. discloses a spring clamp in which the spring clamp member is held against a rigid clamp member using an adjustable bolt. In both these clamps, the cable is retained near an outer edge of the clamp device, which limits the security of the clamping. The cable is also not surrounded by retaining hardware, and so the cable can be lost in the event of clamp slippage.
U.S. Pat. No. 5,435,507 issued to M. W. Murphy discloses a cable support for installation on a rigid pole. This clamp is operatively similar to the Houston clamp except that the spring clamp member is replaced by a second rigid clamp member. The two rigid clamp members are dissimilar.
The present invention contemplates an improved cable clamp which overcomes the aforementioned limitations and others.
According to one aspect of the invention, a cable clamp including two interchangeable half-portions is provided. Each half-portion includes an outer side, an inner side including a cable receiving region, a hinge region arranged below the cable receiving region, and a suspending region arranged above the cable receiving region. The suspending region is adapted to receive an associated support element. The two half-portions are adapted to cooperatively form a unitary cable clamp body having a cable channel defined by the two cable receiving regions and a hinge including the two hinge regions. A tightener is arranged above the cable channel for drawing the half-portions together about the hinge to clamp an associated cable within the cable channel.
According to another aspect of the invention, a piece is disclosed, including an outer side, an inner side having a cable receiving region, a hinge region arranged below the cable receiving region, and a suspending region arranged above the cable receiving region, the suspending region adapted to receive an associated support element. The piece is adapted to cooperate with a similar piece to form a unitary cable retaining body having a cable channel defined by cooperating cable receiving regions, a hinge including cooperating hinge regions and an associated hinge fastening element, and a clamping element arranged to pivotally close the cooperating pieces about the hinge.
According to another aspect of the invention, a cable-retaining device is disclosed. A hinged pair of elements are adapted to receive an associated cable therebetween. A clamp is adapted to compress the hinged pair of elements together to fasten about the associated cable.
According to yet another aspect of the invention, a cable clamp is disclosed. A first body member and a second body member cooperate to form a unitary clamp body. The clamp body has a cable channel, a hinge region arranged on a side of the cable channel, and a compression region arranged on an opposite side of the cable channel away from the hinge region. A hinge fastener hingeably attaches the first and second body members in the hinge region. A clamp draws the first and second body members together in the compression region to compressively hold an associated cable arranged within the cable channel.
According to still yet another aspect of the invention, a cable clamp is disclosed. A left clamp member and a right clamp member together define a clamp body. A hinge is formed into a lower portion of the clamp body. A tightening member is disposed in an upper portion of the clamp body. A cable channel formed into the clamp body is arranged between the hinge and the tightening member.
One advantage of the present invention is that the clamp body is constructed from two identical, interchangeable portions, which simplifies manufacturing and assembly.
Another advantage of the present invention is that it includes a clamping operation employing a nondetachably attached hinge and captive hardware to reduce or eliminate the number of separate parts which must be assembled in the field.
Another advantage of the present invention is that the cable is securely retained in a cable channel arranged away from edges of the clamp.
Another advantage of the present invention is that the clamp can be pre-assembled and placed as a single unit onto a hot, electrified cable using an insulated lifting pole. This simplifies installation of the suspension clamp onto hot wires, and makes the installation safer.
Another advantage of the present invention is that the clamping action occurs horizontally (i.e., left-and-right) at right angles to the cable weight-induced bending stress.
Yet another advantage of the present invention is that the bolt-and-nut fasteners are received by recesses adapted to receive at least one of the bolt head and the nut in non-rotatable fashion. In this way, the bolt-and-nut fastener can be tightened using only the bolt head or only the nut.
Still yet another advantage of the present invention is that the clamp includes one or more cushions that reduce mechanical stress on bending portions of the clamped cable.
Numerous additional advantages and benefits of the present invention will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments.